The present invention relates to a jet engine thrust reverser system and, more particularly, to a thrust reverser system that includes a torque limiter coupled to synchronization mechanisms that ensures the thrust reverser components move in a substantially coordinated manner.
When jet-powered aircraft land, the landing gear brakes and imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required amount of runway distance. Thus, jet engines on most aircraft include thrust reversers to enhance the stopping power of the aircraft. When deployed, thrust reversers redirect the rearward thrust of the jet engine to a forward direction to decelerate the aircraft. Because the jet thrust is directed forward, the jet thrust also slows down the aircraft upon landing.
Various thrust reverser designs are commonly known, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. Each of these designs employs a different type of moveable thrust reverser component to change the direction of the jet thrust.
Cascade-type thrust reversers are normally used on high-bypass ratio jet engines. This type of thrust reverser is located on the circumference of the engine""s midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes. The moveable thrust reverser components in the cascade design includes several translating sleeves or cowls (xe2x80x9ctranscowlsxe2x80x9d) that are deployed to expose the cascade vanes.
Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser components to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and may form the rear part of the engine nacelle.
Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser components. In the deployed position, these doors extend outwardly from the nacelle to redirect the jet thrust.
The primary use of thrust reversers is, as noted above, to enhance the stopping power of the aircraft, thereby shortening the stopping distance during landing. Hence, thrust reversers are primarily deployed during the landing process to slow the aircraft. Thereafter, when the thrust reversers are no longer needed, they are returned to their original, or stowed, position.
The moveable thrust reverser components in each of the above-described designs are moved between the stowed and deployed positions by means of actuators. Power to drive the actuators may come from one or more drive motors, or from a hydraulic fluid system connected to the actuators, depending on the system design. One or more synchronization mechanisms, such as flexible rotating shafts, may interconnect the actuators (and drive motors, if included) to maintain synchronous movement of the moveable thrust reverser components. One problem with this arrangement, however, is that secondary damage to various portions of the thrust reverser system may result under certain failure modes. For example, if one of the actuators becomes jammed, all of the driving force from the remaining operable actuators is concentrated, via the synchronization mechanisms, on the jammed actuator. This may result in damage to actuator system components, including the motors (if included), actuators, synchronization mechanisms, or the moveable thrust reversers components. One solution is to use stronger components, but this increases the cost and weight of the thrust reverser system.
Hence, there is a need for a thrust reverser system that improves upon one or more of the drawbacks identified above. Namely, a system that reduces the likelihood of secondary component damage if thrust reverser system fails, for example, by a jammed actuator, without having to increase the cost and/or the weight of the thrust reverser system components.
The present invention relates to a jet engine thrust reverser system that includes a torque limiter coupled to the synchronization mechanisms that maintain the thrust reversers in substantial synchronism with each other, thereby limiting potential system damage under certain failure modes.
In an aspect of the present invention, a control system for moving a thrust reverser includes first and second actuators, first and second synchronization mechanisms, and a torque limiter. The first and second actuators are operably coupled to receive a driving force to thereby move first and second thrust reverser components, respectively, between stowed and deployed positions. The synchronization mechanisms mechanically couple the first and second actuators and are configured to maintain the actuators in substantial synchronization with one another upon receipt of the driving force by the actuators. The torque limiter is operably coupled between the two synchronization mechanisms, and is activated upon a predetermined torque value being reached between the operably coupled synchronization mechanisms.